Tissues are composed of

Tissues are composed of cells. A tissue is a group of similar cells that perform a specific function. There are four primary types of tissues in the human body: epithelial, connective, muscle, and nervous tissues. Each type of tissue has a distinct structure and function that contributes to the overall physiology of the body.

References:

Junqueira's Basic Histology: Text and Atlas by Anthony L. Mescher

Human Anatomy & Physiology by Elaine N. Marieb and Katja Hoehn